Selector switch



' C. l. BAKER sELcToR SWITCH Filed Nov. 2. 1923 1y MAW Patented Oct. 27, 1925.

UNITED STATES PATENT OFFICE.

CLARENCE I. BAKER, OF ELIZABETH, NEW

JERSEY, I ASSIGNO'R TO \VESTERN ELECTRIC COMPANY, INCORPORATED, OF NEW YORK, N. Y., A CORPORATION OF NE- .7V YORK.

SELECTOR SWITCH.

Application filed November 2, 1923. Serial No. 672,323.

To all to from 2 may cancer-)2 Be it known that I, CLARENCE I. BAKER, a citizen of theUnite'd States of America, residing at Elizabeth, in the county of Union and State of New Jersey, have inrente-d certainnew and useful Improvements in Selector Switches, ofw hieh thefollowi-ng is a full, clear, :concise, and exact description.

The object of this invention is to provide an improved selector switchoi simple and inexpensive construction for use in automatic telephone systems-in various capacities, such as aline finder, li-ne switch, or register.

In switches of this general type such as are shown in the patents to Dietl No. 1,126,727 (February 2, 1915) and to Adams No. 1,399,728 (December 13, 19211), considerable diliiculty has been wencoun't red, due, amongwothercauses, to bouncing brushes and the wide variation in load, particularly what is :knownns the double load, :a condition whiclraexists "momentarily when the diametrically :disposed brushes are both in physical contact one with the last terminal in'the selectorbank..and'-tl1e other with the armrofthe feeder .l'n'usl1,'situate(l at :the opposite'end'of the arc of the terminal bank.

A feature (of this invention ilS an arrangement-whereby the energy transmitted to the moving member of the switch .is distributed more evenly by eliminating the feeder brushesiusually used in switches of thistype.

Another-"feature of this invention is the provision of a bank of parallel layers-of insulated zterminals interspa'ced .withxinsulated strips of metal so arranged that commutation is efiected by -::drawing a single ibl'LlSl] over the .CllClS of twoadjacent arcs,-oneconsisting 013a serrated strip of metal and :the otherof .a layer of .terminals, t-he combination thus constituting both a feeder :and a rotor for the individual terminals comprising the unit.

Another Ifeature pot-this invention is the method of con'miutation, whereby brush bouncing, one of the principal drawbaeksof selector switches of this design is eliminated.

Other features will. appear *from the detailed description.

Fig. 1 is aside 'view of the switch; Fig. 2 is a detailed drawing ofone of the double brushes 9, Fig.3 isthe section33 oi Fig.

1; Fig. at is a plan view of the double brushes 9 and the terminals and feeder strips of the section 38, Fig. 1 and Fig. 5 is a detailed drawing of a non-bridging brush as distinguished from a bridging brush shown in Fig. 2.

The individual insulated terminals 1, are arranged in the form of the are of a circle, and are separated from the serrated strip of metal 2, arc-uate in form, by a layer of insulation 4, thus the individual terminals 1 are insulated from the serrated strip of metal 2, and from each other. The indiridual terminals are spaced so as to appear opposite the gaps 10 in the serrated metal strip as indicated in Figs. 1 and 4. The are of insulated terminals and the serrated metal strip together with the insulating material. 1 form a unit, and a number of these units, usually six, are placed in juxtaposition to form a terminal bank, the whole being secured to the main frame 6 by the screws 5, and the metal strip 11.

The -brushes.9 are attached at 7 by means of rivets to a metal carrier 8 and are thereby electrically connected together. Each pair of brushes 9 is connected to a separate carrier 8 andall the carriers are insulated from each other and mounted upon the shaft 12 to form the rotary unit or rotor.

The-usual driving unit 13, consisting of an electromagnet 14, with its armature 15 pivoted at 37, carrying the arm 16, to which is secured the pawl 17 for stepping the ratchet 18, is attached to the main frame 6 by means of the screw 21. The ratchet 18 which is controlled by the pawl 17 terms a part of the rotor, hence each time the pawl 17 makes a complete stroke, the ratchet 1S, and consequently'the rotor, rotates one step in a counter clockwise direction. To prevent the rotor from-rotating in a clockwise direction, a pawl 19 is provided which normally engages with one ofthe teeth of the ratchet 18. The back-stop 20 limits the downward motion of the pawl 17, thus preventing the rotor from stepping more than one step .at a time. 'The brushes9 are supported by a back-stop 22 which tends to regulate the spacing of the brushes 9, and the limits of their movement.

A spring26, is tensioned between the in 25, forming a part of the framework of t magnet structure. and a lug 2 an extension of the armature 15. When the armature 1'?) type, is wide is attracted by the electromagnet 14:, the lug 27 is moved away from the lug 25 thus tending to increase the tension of the spring 26. The pawl 17 is also brought into engagement with the next succeeding tooth of the ratchet 18, and when the electromagnet 1 1 is deenergized, the spring 26 tends to return the armature 15 to normal, thus forcing the pawl 17 to step the rotor one step. i

To make the stepping magnet 14 self-interrupting, the arm 16 in operating, causes the insulating cap 28 to force the contact spring 29 away from the contact member 30, thus opening the stepping magnet circuit.

Each prong of the brush 9 (Fig. 2) 1s split into two contacting members 23 and 24.- thus insuring better contact between the brush and the terminals. The prongs 31 and 32 (Fig, 2) of the brush 9, are so spaced. that oneof the prongs will always be in contact with the serrated metal strip, and. on the bridging brush (Fig. 2), both prongs will always be in contact with (or bridging) ad acent terminals in the bank, while the brush is moving from terminal to terminal.

()ne prong of the brush n both thgbrldging (Fi 2), and non-bridging (big. a),

enongh to span and make contact with both the serrated metal strip and the individual terminals, and as the individiual'terminals are longer than the flaps 10 in theserrated metal Strip, it is evident that the contacting members will at all times be supported either by the surface of a terminal 1, or that of the serrated strip 2. It is evident that as a continuous bearing, or contacting surface, is thus furnished, the tendency of the brushes to bounce, heretofore experienced in other types of switches, due to the absence of a bearing surface between the terminals, will be eliminated. lVhen the brush 9 is at rest and in the normal position, one of its prongs will be in contact with one of the individual terminals 1, only, the other prong will be in contact with the serrated metal strip 2 only.

The non-bridging type of brush (Fig. is only equipped with one prong 33 wide enough to span both the terminals 1 and the metal strip 2. The other prong 3 1 is only wide enough to make contact with the surface of the serrated metal strip 2, but it 1s elongated so as to span one of the gaps of the metal strip 2. When a non-bridging brush (Fig. 5), is at rest, its prong 33 will be in contact with one of the terminals 1, only, as shown in Fig. 4c, and the trailer Set will be resting upon the contacting surface of:the serrated metal strip.

The serrated metal strips overlap the lay ers of terminals at 35 and 36, and these overlapping extremes are graded, or bevelled, as shown at 35 and 36, thus forming an inclined plane over which the brushes wipe.

This inclined overlap performs several functions. It allows one brush (9) of a pair to make, before its associated brush breaks contact with the serrated metal strip, thus providing a continuous feeder. Due to the bevel a brush does not jar or bounce upon leaving the strip at 35 because the pressure on the brush is gradually reduced. Similarly, due to the bevels at 36 and 35, the load upon the magnet 1 1 is not suddenly increased, because as the pressure on the one set of brushes is reduced at 35, the pressure on the other set of brushes is increased in substantially like proportion at 36. Hence the variation in the load on the magnet 14 is at all times kept within close limits.

What is claimed is:

1. A rotary switch comprising, a plurality of units each consisting of a layer of insulated terminals arcuate in form paralleled by an arcuate serrated metal strip, a rotata ble member equipped with a plurality of wipers, one or more wipers cooperatively associated with each unit and capable of passing over the contacting surfaces there-,

of, thereby electrically connecting said metal strip with the terminals in succession, and electromagnetic means for moving the rotatable member.

2. A selector switch comprising, a plurality of layers of insulated terminals, each layer paralleled by an insulated serrated strip of metal, a movable set of brushes, each brush capable of moving over the ends of the terminals and of the associated serrated metal strip, thereby electrically connecting said serrated strip with said terminals in succession, and electrically controlled stepping means for moving said brushes.

3. A selector switch comprising, a plurality of insulated serrated strips of metal, each strip paralleled by a layer of insulated terminals, with a terminal opposite to and overlapping each serration in the metal strip, the contacting surfaces of the terminals in all of the layers and of all the metal strips being in the same cylindrical surface, a rotatable member equipped with a plurality of wipers, one or more wipers cooperatively associated with each particular strip of metal and its associated layer of terminals, the wipers thereby electrically connecting said metal strip with the terminals in succession, the terminals and serrated strip cooperatively furnishing a continuous brush support, and electromagnetic stepping means for moving the:rotatable member.

4. A rotary selector switch comprising, a plurality of insulated serrated strips of metal, each strip paralleled by a layer of insulated terminals, with aterminal opposite, to and overlapping each serration in the metal strip, the contacting surfaces of the terminals in all the layers and of all of the metal strips being in the same cylindrical surface, a rotatable element including a ratchet wheel and equipped with a plurality of wipers, one or more wipers cooperatively associated with each particular strip of metal and its associated layer of terminals, the wipers thereby electrically connecting said metal strip with the terminals in succession, the terminals and serrated strip cooperatively furnishing a continuous brush support, and stepping means comprising a stepping pawl and motor magnet therefor adapted to rotate the ratchet wheel.

A rotary selector switch comprising a plurality of layers of arcuately arranged and insulated terminals, each layer being paralleled by and insulated from an arcuate metallic feeder strip, a rotatable member having a plurality of sets of oppositely disposed wipers, each set of wipers respectively arranged for cooperation with a layer of terminals and a feeder strip, and driving means for moving said wipers over said terminals and feeder strips, the ends of said feeder strips being beveled whereby when certain of said wipers are leaving engagement with the last terminals of said arcuate layers, the remaining wipers will engage the beveled portions of said strips and a substantially uniform load will be maintained on said driving means.

6. A rotary selector switch comprising a plurality of layers of arcuately arranged and insulated terminals, each layer being paralleled by and insulated from a notched arcuate feeder strip, the terminals of each layer being positioned opposite to and overlapping the notches of its corresponding strip, a rotatable member having a plurality of sets of oppositely disposed wipers, each set of wipers respectively arranged for bridging a layer of terminals and a feeder strip, the contact edgesof said terminals and strips providing a continuous bearing surface for the ends of said wipers, and the ends of said strips being beveled whereby when certain of said wipers are leaving engagement with the last terminals of said arcuate layers the remaining wipers will engage the beveled portions of said strips and a substantially uniform load will be maintained on said driving means.

In witness whereof, I hereunto subscribe my name this 26 day of October A. D., 1923.

CLARENCE I. BAKER. 

